e the Pampas on the east
have been raised only a few inches in the same time. Crossing from the
Atlantic to the Pacific, in a line passing through Mendoza, Mr. Darwin
traversed a plain 800 miles broad, the eastern part of which has emerged
from beneath the sea at a very modern period. The slope from the
Atlantic is at first very gentle, then greater, until the traveller
finds, on reaching Mendoza, that he has gained, almost insensibly, a
height of 4000 feet. The mountainous district then begins suddenly, and
its breadth from Mendoza to the shores of the Pacific is 120 miles, the
average height of the principal chain being from 15,000 to 16,000 feet,
without including some prominent peaks, which ascend much higher. Now
all we require, to explain the origin of the principal inequalities of
level here described, is to imagine, first, a zone of more violent
movement to the west of Mendoza, and, secondly, to the east of that
place, an upheaving force, which died away gradually as it approached
the Atlantic. In short, we are only called upon to conceive, that the
region of the Andes was pushed up four feet in the same period in which
the Pampas near Mendoza rose one foot, and the plains near the shores of
the Atlantic one inch. In Europe we have learnt that the land at the
North Cape ascends about five feet in a century, while farther to the
south the movements diminish in quantity first to a foot, and then, at
Stockholm, to three inches in a century, while at certain points still
farther south there is no movement.

But in what manner, it is asked, can we account for the great lateral
pressure which has been exerted not only in the Andes, Alps, and other
chains, but also on the strata of many low and nearly level countries?
Do not the folding and fracture of the beds, the anticlinal and
synclinal ridges and troughs, as they are called, and the vertical, and
even sometimes the inverted position of the beds, imply an abruptness
and intensity in the disturbing force wholly different in kind and
energy to that which now rends the rocks during ordinary earthquakes? I
shall treat more fully in the sequel (end of chap. 32) of the probable
subterranean sources, whether of upward or downward movement, and of
great lateral pressure; but it may be well briefly to state in this
place that in our own times, as, for example, in Chili, in 1822, the
volcanic force has overcome the resistance, and permanently uplifted a
country of such vast